mineral

Banded Agate (Orca Agate)

Silicon Dioxide (SiO2) - Chalcedony variety

Hardness: 6.5-7 on Mohs scale; Color: Grey, blue, white, and black banding; Luster: Waxy to vitreous; Crystal structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Hardness: 6
Color: Grey, blue, white, and black banding
Luster: Waxy to vitreous

Identified April 16, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Grey, blue, white, and black banding; Luster: Waxy to vitreous; Crystal structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Formation & geological history

Formed as a result of silica-rich groundwater filling cavities (vugs) in volcanic or sedimentary rocks over thousands of years; predominantly found in Madagascar for this specific color pattern.

Uses & applications

Primarily used for ornamental purposes, lapidary art, jewelry, and as a collector's specimen for spiritual/metaphysical practices.

Geological facts

This specific variety is nicknamed 'Orca Agate' due to its resemblance to the skin patterns of a Killer Whale. Agates often form in concentric layers that record the chemistry of the water as it percolates through rock.

Field identification & locations

Identify by its characteristic banding, waxy feel when polished, and transclucency when held to light. It is commonly found in basaltic geodes in Madagascar.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

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metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral